There are numerous methods available for affixing photovoltaic cells to residential and commercial roofing structures. The most common photovoltaic roofing product consists of a stand-alone solar panel, which mounts to an existing roof or structure, using frame supports or direct mounting to the structure. These products are used in addition to, and not in place of, existing roof structures. The wiring systems for these photovoltaic arrays use traditional parallel or series circuits, and standard crimp or lug type connections.
In terms of standard roofing products, there are various examples of interlocking shingle type products made from a range of materials, including plastic, foam, and metals. These materials have been used in place of more traditional shingle material, such as baked clay, slate, cedar, and asphalt. While these alternative materials compensate for the weaknesses of the traditional designs, such as dimensional instability, weight, and environmental concerns, they do not provide a solution to problems associated with traditional installation methods. The installation methods for the plastic or resinous shingles are similar to traditional shingle installation methods, in that they use nails to affix the tiles to the roof directly or to the roofing battens. Typical products of this type, for example, can be found in the following Canadian Patent Nos. 746,203, 2,301,420, and 2,219,026.
With the popularity of photovoltaic roofing systems increasing year to year, there have been a number of products introduced that combine the plastic material shingles with integrated solar cells. The solar cells can be photovoltaic, or in some cases provisions are included in the tile to provide solar heating of water channels for building hot water supply. For photovoltaic systems, stand alone panels have been developed to mount to existing roof structures. In the cases where the photovoltaic cell has been mounted to a shingle, the installation methods remain traditional, in that the entire system is either nailed or screwed to the roof structure. The electrical wiring methods for these systems involve standard industry connectors and harnesses. Typical products of this type can be found in the following Canadian Patent Nos. 2,335,159, 1,248,582, and 1,077,226, and U.S. Pat. No. 6,856,496.
Photovoltaic systems and the use of alternative materials in roofing products have been able to achieve commercial success in niche markets. An apparent shortcoming of prior known systems is that all inter-panel and inter-shingle wiring connections as well as any feed connections from the panels to the house has had to be performed manually and on a one-by-one basis.
The assembly of photovoltaic systems to building structures has resulted in a number of products that use rail or track type systems to structurally attach photovoltaic panels to building structures or roofs. These products advantageously use the rail systems as raceways or conduits for the photovoltaic wiring. The use of metal or plastic rails allows for a structural framing and attachment method for the photovoltaic panels while providing enclosed pathways to environmentally protect the electrical systems. An apparent disadvantage to the rail systems is that the assembly of the photovoltaic panels is accomplished either with mechanical fasteners or chemical bonding. The electrical wiring of these systems are traditional wiring harnesses and connectors, and do not provide a solution to simplifying the installation of the photovoltaic systems to a building structure. Typical products of this type can be found in the following U.S. Pat. Nos. 6,065,255, 6,111,189, 6,465,724, 6,672,018, and 7,012,188.
The combination of continuous lengths of rail that act as a busway to interconnect photovoltaic panels has been considered in U.S. Pat. No. 6,201,180. This design provides a solution to transforming the electrical output of a photovoltaic panel from DC current to AC current. The design of this busway enables the electrical connection of photovoltaic panels using plug receptacles that mate to an electrical conduit and can interconnect multiple independent photovoltaic panels. While this system provides a solution for electrical interconnectivity of photovoltaic panels, it does not provide a structural fastening system for photovoltaic roof tiles.